A vaccine against dengue made with weakened virus, very safe
Em meio a uma das piores ondas de dengue da história recente, o Brasil se vê diante de um paradoxo doloroso: doses de vacina disponíveis, ciência comprovada, necessidade urgente — e ainda assim, hesitação. O Ministério da Saúde ampliou a faixa etária elegível para a vacinação, de 10 a 11 anos para 10 a 14 anos, não por falta de planejamento, mas porque a confiança pública ainda não acompanhou o ritmo da crise. É um lembrete de que, na saúde coletiva, a eficácia de uma vacina nunca é apenas científica — é também humana.
- Das 1,2 milhão de doses distribuídas em 521 municípios, apenas 250 mil foram aplicadas até o início de março — um ritmo que ameaça desperdiçar um recurso escasso em plena epidemia.
- Crianças e adolescentes de 10 a 14 anos representam o grupo com maior número de internações por dengue depois dos idosos, com 16.400 hospitalizações registradas em menos de cinco anos.
- O Ministério da Saúde tomou uma decisão tática: ampliar a faixa etária elegível para evitar que doses vencidas se tornem símbolo de uma oportunidade perdida.
- A vacina Qdenga, desenvolvida pela Takeda ao longo de mais de uma década, oferece 80% de eficácia com efeitos colaterais mínimos — e agora é gratuita nas unidades públicas de saúde.
- Pediatras como Natália Bastos alertam: o obstáculo não é mais o acesso nem o custo, mas a hesitação dos pais diante de uma vacina segura e comprovada.
- A corrida agora é contra o tempo — doses com prazo de validade, uma epidemia em curso e a esperança de que abrir mais portas leve mais famílias a atravessá-las.
O Brasil enfrenta esta semana um paradoxo incômodo: vacinas contra dengue disponíveis em larga escala, mas poucos braços dispostos a recebê-las. Das 1,2 milhão de doses distribuídas pelo Ministério da Saúde em 521 municípios de 16 estados, apenas 250 mil haviam sido aplicadas até o início de março. Diante do risco de desperdício e com doses próximas ao vencimento, o governo tomou uma decisão: ampliar a faixa etária elegível de 10 a 11 anos para 10 a 14 anos.
A escolha do público-alvo original não foi arbitrária. Entre janeiro de 2019 e novembro de 2023, crianças e adolescentes dessa faixa etária acumularam 16.400 internações por dengue — o grupo mais afetado depois dos idosos. A vacina escolhida, a Qdenga da Takeda, é resultado de mais de uma década de desenvolvimento. Não é experimental: duas doses oferecem cerca de 80% de proteção, com efeitos colaterais leves e passageiros.
A pediatra Natália Bastos, com 15 anos de experiência em Brasília, resume o que está em jogo. A vacina é segura, estudada e eficaz — e agora é gratuita nas unidades públicas, um contraste marcante com os R$ 400 a R$ 500 cobrados em clínicas privadas. Ela pede que os pais não esperem.
O que torna este momento revelador vai além dos números epidemiológicos. O Estado tinha as ferramentas. A ciência estava do lado da saúde pública. Mas a confiança popular não acompanhou. Ampliar a elegibilidade é uma aposta: que mais acesso produza mais adesão, antes que o tempo — e as doses — se esgotem.
Brazil's Health Ministry faced a familiar problem this week: a vaccine campaign that wasn't gaining traction. Of the 1.2 million doses of dengue vaccine distributed across 521 municipalities in 16 states, only 250,000 had been administered by early March. The numbers were presented Friday by Eder Gatti, director of the National Immunization Program, and they told a story of hesitation at a moment when the country could not afford it.
The initial strategy had been straightforward: vaccinate children aged 10 and 11, the age group that fills hospital beds with dengue cases more than any other except the elderly. Between January 2019 and November 2023, this cohort accounted for 16,400 dengue hospitalizations—a staggering concentration of illness in a narrow slice of the population. But uptake was sluggish, and doses were approaching expiration. So the ministry made a tactical decision: expand the eligible age group to include teenagers 12 to 14 years old, widening the net in hopes of using the vaccine before it expired.
The vaccine in question, Qdenga, is manufactured by Takeda and represents a significant shift in Brazil's dengue response. For more than a decade before the pandemic, the company had been developing this live-attenuated vaccine—a weakened form of the virus itself. It is not new, not rushed, not experimental. Two doses provide roughly 80 percent protection against dengue infection. The side effects are minimal: a light fever perhaps, some body aches, maybe a rash that appears around day ten. These are trivial compared to what dengue itself can do.
Pediatrician Natália Bastos, who has worked in Brasília for over 15 years treating newborns through adolescents, sees the stakes clearly. She spoke to the Brazilian news agency about the surge in dengue cases and what parents need to understand. The vaccine is safe, she emphasized. It has been studied extensively. It works. And now it is free—available at public health centers without cost, a stark contrast to the R$400 to R$500 price tag it carried in private clinics. She urged parents to bring their children to vaccination sites immediately, not to wait, not to hesitate.
What makes this moment significant is not just the epidemiology, though that is urgent. It is the collision between a proven public health tool and the friction of public trust. The ministry had the doses. The science was solid. The need was undeniable. Yet people were not coming. So the government widened the door, hoping that more access would translate to more arms vaccinated before the window closed. Whether that calculation proves correct will become clear in the weeks ahead. For now, the vaccine sits in health centers, waiting.
Citas Notables
It is a vaccine against dengue made with weakened virus, a very safe vaccine. It has been in development since before the pandemic, so it is not new, not developed in haste.— Pediatrician Natália Bastos
The vaccine is available now at public health centers, free of charge. I urge all parents to seek vaccination for children aged 10 to 11 with urgency.— Pediatrician Natália Bastos
La Conversación del Hearth Otra perspectiva de la historia
Why did uptake lag so badly if the vaccine was already approved and available?
That's the question the ministry was asking too. It wasn't a safety issue—the vaccine had been in development for years. It may have been simple inertia, or parents waiting to see if others went first, or just the friction of getting a child to a clinic. But with doses expiring, they couldn't afford to wait for demand to build naturally.
So expanding to 12-14 year-olds was a way to use up inventory before it went bad?
Partly that, yes. But it also made epidemiological sense. The data showed that hospitalizations were concentrated in that 10-14 age band. Expanding the eligible group meant more potential recipients in the same geographic areas where the vaccine was already distributed.
The pediatrician mentioned the vaccine cost R$400-500 privately. Why such a gap between private and public?
That's the usual story—private clinics pay retail prices, public systems negotiate bulk rates. But it also signals something: this vaccine was never going to reach poor families through the private market. Making it free through the SUS was the only way to vaccinate at scale.
Is 80 percent efficacy considered good for a dengue vaccine?
Very good. Dengue vaccines are notoriously difficult to develop. This one prevents infection in four out of five vaccinated people. That's substantial protection, especially in a population where the disease is endemic.
What happens if uptake still doesn't improve even with the expanded age group?
Then the ministry faces a harder choice: either extend eligibility further, or accept that some doses will expire unused. But they're betting that removing the age barrier will be enough to move the needle.